The ornamental design for a firepit, as shown and described.
FIG. 1 is a top, front, right perspective view of a fire pit showing our design;
FIG. 2 is a front view thereof;
FIG. 3 is a left side view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a rear view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The even-length broken lines shown in the drawings are for the purpose of illustrating portions of the article and form no part of the claimed design. The long-short broken lines depict boundaries of the claimed design and form no part thereof.